Titre du document / Document title

Unit-cell intergrowth of pyrochlore and hexagonal tungsten bronze structures in secondary tungsten minerals

Auteur(s) / Author(s)

GREY Ian E. ⁽¹⁾ ; BIRCH William D. ⁽²⁾ ; BOUGEROL Catherine ⁽³⁾ ; MILLS Stuart J. ^{(1 2)} ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

⁽¹⁾ CSIRO Minerals, Box 312, Clayton South, Vic. 3169, AUSTRALIE
⁽²⁾ Geosciences Department, Museum Victoria, GPO Box 666, Melbourne, Vic. 3001, AUSTRALIE
⁽³⁾ Equipe CEA-CNRS NPSC SP2M/DRFMC/CEA, 17 rue des Martyrs, 38054 Grenoble, FRANCE

Résumé / Abstract

Structural relations between secondary tungsten minerals with general composition A_x[(W,Fe)(O,OH)₃]_yH₂O are described. Phyllotungstite (A = predominantly Ca) is hexagonal, a = 7.31(3)Å, c = 19.55(1)Å, space group P6₃/mmc. Pittongite, a new secondary tungsten mineral from a wolframite deposit near Pittong in Victoria, southeastern Australia (A = predominantly Na) is hexagonal, a = 7.286(1)Å, c = 50.49(1)Å, space group P-6m2. The structures of both minerals can be described as unit-cell scale intergrowths of (111)_py pyrochlore slabs with pairs of hexagonal tungsten bronze (HTB) layers. In phyllotungstite, the (111)_py blocks have the same thickness, 6 Å, whereas pittongite contains pyrochlore blocks of two different thicknesses, 6 and 12 Å. The structures can alternatively be described in terms of chemical twinning of the pyrochlore structure on (111)_py oxygen planes. At the chemical twin planes, pairs of HTB layers are corner connected as in hexagonal WO₃.

Revue / Journal Title

Journal of solid state chemistry   ISSN 0022-4596   CODEN JSSCBI 

Source / Source

2006, vol. 179, n^o12, pp. 3860-3869 [10 page(s) (article)] (20 ref.)

Langue / Language

Anglais

Editeur / Publisher

Elsevier, San Diego, CA, ETATS-UNIS  (1969) (Revue)

Mots-clés anglais / English Keywords

Transition element compounds ; Inorganic compounds ; Tungsten oxides ; Bronze type compound ; Tungsten bronze ; Hexagonal lattices ; Pyrochlore type compound ; Transition elements ; Cellular structure ; Crystal twin ; Crystal defects ; Twinning ; Size effect ; Thickness ; Pyrochlore ; Space groups ; Actinides ; Iron ; New mineral ; Intergrowth ; Unit cell ;

Mots-clés français / French Keywords

6166 ; WO3 ; O W ; W ; Métal transition composé ; Composé minéral ; Tungstène oxyde ; Bronzes ; Bronze tungstène ; Réseau hexagonal ; Pyrochlores ; Métal transition ; Structure cellulaire ; Macle ; Défaut cristallin ; Maclage ; Effet dimensionnel ; Epaisseur ; Pyrochlore ; Groupe espace ; Actinide ; Fer ; Minéral nouveau ; Intercroissance ; Maille cristalline ;

Mots-clés espagnols / Spanish Keywords

Bronces ; Pirocloros ; Macla ; Mineral nuevo ; Intercrecimiento ;

Mots-clés d'auteur / Author Keywords

Chemical twinning of pyrochlore ; Structures of secondary tungsten minerals ; Unit-cell intergrowth structures ; Pittongite ; Phyllotungstite ;

Localisation / Location

INIST-CNRS, Cote INIST : 14677, 35400014522719.0340